Vehicle pyrotechnic circuit breaker circuit

Abstract

The present disclosure provides a "Vehicle Pyrocut Circuit". A vehicle electrical system includes a high voltage bus and a pyro fuse designed to mechanically interrupt the bus when activated. Activation is triggered by a control command based on an excessive current in the loop or by a short circuit in the loop. The system uses switches to power the squib inside the pyro fuse. Each switch gate is connected to a resistor that is connected to the power supply through a disconnection switch. The squib driver can also activate the pyro fuse independently.

Description

Technical Field

[0001] This disclosure relates to vehicle electrical systems. Background Technology

[0002] Automotive electronics and wiring systems are typically built around a network of interconnect modules, sensors, actuators, and power distribution components. The foundational component is the wiring harness, which comprises bundled wires and connectors laid throughout the vehicle. These harnesses carry both electrical and data transmissions between components. Summary of the Invention

[0003] In one example, a vehicle electrical system includes a high-voltage bus and a pyrofuse. The pyrofuse interrupts the bus when activated. Activation is controlled by a pair of switches and a disconnect circuit. When the circuit is disconnected, the switches power the pyrofuse. The switches are field-effect transistors (FETs), specifically N-channel MOSFETs. Each gate is connected to a resistor. These resistors are connected to the power supply via a disconnect switch. The pyrofuse includes a squib. One FET connects its source to a squib pin, and another FET connects its drain to another squib pin. The drain of one FET is connected to the power supply via a switch, while the source of the other FET is connected to ground. A squib driver can also activate the pyrofuse. The driver is connected to the power supply via a disconnect switch. A controller monitors the bus current. If the current exceeds a threshold, the controller commands the driver to activate the pyrofuse. All components, including the pyrofuse and switches, are housed in a housing.

[0004] In another example, a pyrotechnic fuse is activated in response to a broken circuit. A pair of field-effect transistors switch from inactive to active. They then supply power to the bursting tube in the pyrotechnic fuse. The pyrotechnic fuse activates and interrupts the high-voltage bus. A bursting tube driver can be commanded to power the bursting tube. This command is triggered when the current on the bus exceeds a set value.

[0005] In another example, a vehicle includes a high-voltage bus and a cutoff circuit. It has a disconnect box with a pyrotechnic fuse. The pyrotechnic fuse interrupts the bus when activated. When the cutoff circuit is open, an activation system supplies power to the pyrotechnic fuse. A bursting tube driver can also activate the pyrotechnic fuse upon command. The disconnect box includes power supplies for both the activation system and the bursting tube driver. The activation system contains two switches. The switches respond to the disconnect circuit being open. The switches are metal-oxide-semiconductor field-effect transistors. The vehicle includes a 12V battery that can be connected to the disconnect box. A controller monitors the bus current. If the current exceeds a threshold, the controller issues a command to activate the pyrotechnic fuse. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the vehicle's electrical system, including the pyrotechnic actuator. Detailed Implementation

[0007] Detailed embodiments are described below. These examples are illustrative and not intended to limit the scope of the subject matter, which can take various alternative forms. The drawings are not drawn to scale. Certain features may be enlarged or reduced to highlight specific aspects of the components. Therefore, the structural and functional details provided should be understood as representative and intended to guide those skilled in the art to apply the described concepts in different ways.

[0008] A vehicle's electrical distribution system may include a 12V or 48V battery, a fuse box, and relays. Power is delivered to individual loads via dedicated circuits that include fuses or circuit breakers. Relays are used to switch high-current devices using low-current control signals. The main fuse box or distribution center is typically located near the battery and serves as a central hub for routing high-current power.

[0009] Control modules, known as Electronic Control Units (ECUs) or Vehicle Control Units (VCUs), are distributed throughout the vehicle architecture. Each ECU or VCU manages different subsystems. Typical subsystems include engine control (if an engine is present), transmission management, exterior and interior lighting, body electronics, infotainment, power steering, and driver assistance features. These control units operate using embedded microcontrollers or microprocessors, typically with integrated memory, analog-to-digital converters, and pulse-width modulation (PWM) outputs. Communication between modules occurs via in-vehicle networking protocols. The most common networks include: Controller Area Network (CAN), which supports real-time communication between the powertrain and chassis systems; Local Area Network (LIN), used for lower-speed applications such as mirror adjustment or window control; and Automotive Ethernet, which supports high-bandwidth data exchange between cameras, sensors, and infotainment systems. Some ECUs support multiple communication protocols simultaneously. Each module interfaces with the vehicle wiring harness via multi-pin connectors, which are typically sealed and keyed to prevent misconnection. These connectors route power, ground, sensor inputs, actuator outputs, and communication lines. Signal integrity is maintained through proper shielding, the use of twisted-pair cabling for differential signals, and terminating resistors when necessary.

[0010] Sensors are distributed throughout the vehicle and provide real-time input to the ECU and VCU. Each sensor is designed to measure a specific physical parameter. Common sensor types include thermistors for temperature measurement, strain gauges or piezoresistive elements for pressure sensing, variable magnetoresistive or Hall effect sensors for detecting rotational speed, and potential or magnetic encoders for position sensing. Current sensors are also commonly used and include Hall effect sensors that detect the magnetic field generated by a current-carrying conductor, and shunt-based sensors that measure the voltage drop across a precision resistor to infer the current. More advanced implementations can use fluxgate or magnetoresistive sensing elements to achieve higher accuracy and sensitivity. These current sensors are used in applications such as traction inverters, battery management systems, on-board chargers, electric power steering, and fuse monitoring circuits. The output signal from a current sensor can be analog or digital and can include built-in isolation, signal conditioning, or diagnostic features, depending on the specific application requirements. Many sensors use analog voltage or current signals to transmit data, while others use digital protocols such as SENT (Single-sided nibble transmission), PWM, or LIN. Sensor power is typically supplied at 5V or 12V levels via vehicle wiring harnesses, depending on the sensor type and subsystem requirements. The ground return path is routed through the harness back to the common ECU ground or vehicle chassis. Signals from the sensors are routed via shielded or twisted-pair cables to reduce noise and electromagnetic interference. Actuators receive output signals from the ECU or VCU in response to sensor inputs and internal logic. Actuators include solenoids, electric motors, servo mechanisms, relays, valves, and stepper motors. Control signals can be binary (on / off), analog (variable voltage or current), or digital (e.g., CAN-based commands for smart actuators). Some actuators include internal position feedback or diagnostic communication capabilities. Actuation control is typically implemented using PWM signals, H-bridge drivers for bidirectional control, or direct voltage control, depending on the application and load type.

[0011] High-current circuits used in systems such as starter motors, electric steering systems, and electric compressors employ thick-gauge wires and specialized connectors. These circuits may include wire-to-wire connectors with built-in current sensing or thermal protection elements.

[0012] The lighting systems are laid out separately from their own circuitry for the headlights, taillights, and interior lights. These circuits are controlled by the body control module and may include pulse width modulation (PWM) for brightness control.

[0013] Modern high-voltage power transmission systems may include circuitry for managing electrical faults. Traditionally, this has been achieved using mechanical contactors and fuses that interrupt current flow in the event of a fault.

[0014] A newer method involves using pyrotechnic circuit breakers or pyrotechnic fuses, which rely on a small amount of charge to interrupt the conductive path. At its core is a metal busbar, typically made of copper, which carries current during normal operation.

[0015] The device may include a pyrotechnic actuator called a burst tube, similar to those used in other systems. When triggered by an electrical signal, the burst tube produces a controlled response, applying force to a weakened section of the busbar, causing it to break.

[0016] The entire assembly can be housed in a molded housing that shields and insulates the internal components. Some designs include arc suppression features for managing high-voltage disconnections. Some pyrotechnic fuse configurations receive trigger signals via an electrical interface connected to the vehicle's control system. Certain models also include an internal power source, such as a capacitor or battery, allowing activation even when mains power is unavailable.

[0017] Upon activation, the burst tube directly disconnects the busbar or drives the blades through the busbar. This creates a permanent open circuit within milliseconds. The pyrotechnic fuse is typically replaced after activation. Compared to conventional fusible fuses and mechanical contactors, pyrotechnic fuses offer faster response times and, in some cases, a more compact form factor when handling similar voltage and current levels.

[0018] Some pyrotechnic fuse arrangements may have design and implementation constraints. They require a consistent power supply to activate the triggering mechanism, and their integration depends on components and control software that meet automotive system standards. In the absence of mechanical contactors capable of isolating both full voltage and full current, addressing all operating scenarios in high-voltage power distribution systems may require additional considerations.

[0019] In certain operating conditions (such as complete power outages or severe electrical faults), vehicles may lack a conventional control path. In these situations, the ability to actuate pyrotechnic fuses using alternative paths may be required. A ruggedized activation system provides a means to trigger pyrotechnic fuses in these scenarios, including environments with power degradation or communication disruptions.

[0020] Some proposed pyrotechnic circuit breakers rely on MOSFET triggers controlled by a ground loop, rather than integrated circuits or dedicated pyrotechnic tube drivers. A small internal power supply with low leakage current allows the system to remain operational for extended periods after a low-voltage power loss.

[0021] The design includes, for example, an N-channel MOSFET. Its gate pin is typically held at the same potential as the source pin, thus keeping the device off. To activate the MOSFET, a voltage difference must be generated between the gate and source. This is achieved using a pull-up resistor on the gate pin. The resistor has a high resistance value to reduce leakage.

[0022] The system uses a loop called a cutoff loop, which typically connects the gate and source pins to ground. The main components of the cutoff loop are insulated copper wires, usually sheathed in a thermoplastic material rated for automotive environments. These wires are routed through specific areas of the vehicle where interruptions may occur, such as along structural members, body panels, sensors, or manually accessible points. The loop may include intermediate connectors or joints, but these should maintain a continuous electrical connection under normal conditions. At the MOSFET interface, the loop can be soldered or crimped to the gate and source terminals to create a low-resistance path to keep the transistor disabled.

[0023] A pull-up resistor can be connected between the gate and a higher voltage potential (typically an internal energy storage node). This resistor has a high value, typically in the range of hundreds of kiloohms to megaohms, which limits leakage current while providing a default high state when the loop is broken. The resistor is not physically part of the loop, but it functions to set the gate voltage once the loop is broken.

[0024] The cut-off circuits can be arranged in several ways depending on the application. A single continuous circuit can be laid out through multiple locations to create redundant breakpoints. Alternatively, several or sequential circuit segments can be used, each circuit segment being laid out to a different part of the vehicle. The design may also include intentionally weakened sections or mechanical interfaces that may separate under specific conditions, such as during structural deformation or when a panel is removed.

[0025] Deployment strategies vary depending on physical constraints and triggering requirements. Some implementations route the circuit through molded guides, spacers, or brackets to stabilize its path and prevent accidental disconnection. Other methods use shielding and strain relief to integrate the circuit into the vehicle's wiring harness to maintain integrity during operation. If integration with electronic components is required, the circuit can also be printed onto flexible or rigid circuit boards.

[0026] The termination of the disconnect circuit at the activation circuit should take into account electromagnetic noise, vibration, and environmental exposure. Depending on system-level noise considerations, this may include shielded cables, twisted-pair cabling, or filter components.

[0027] When the circuit is mechanically or electrically disconnected, the gate voltage rises due to the pull-up resistor, activating the MOSFET and allowing current to flow to downstream loads, such as pyrotechnic fuses. In other words, the gate pin voltage rises through the pull-up resistor. This causes the MOSFET to close and delivers power directly to the pyrotechnic fuse. The circuit reacts rapidly, with switching times in the nanosecond range. Even when the low-voltage system is offline, allowing the disconnect circuit through structural components enables rapid high-voltage disconnection.

[0028] In one example, a system includes an 18-farad supercapacitor and a small-volume printed circuit board. The system can remain operational for hours or days after a power outage and is software-independent. Using a disconnect-activation method also reduces the chance of failure due to open wiring in the disconnect loop.

[0029] This activation system provides a method for controlling pyrotechnic fuses. It simplifies design in some cases and allows for the rapid disconnection of high-voltage circuits without relying on complex electronics or software.

[0030] refer to Figure 1 Vehicle 10 includes a high-voltage disconnect mechanism based on a pyrotechnic fuse, which is activated by a burst tube actuator or a triggering system based on a redundant disconnect circuit. The components in this example are organized into functional subsystems, some of which are further nested within a larger system housing, thus adhering to a modular electrical architecture. Other arrangements are also conceivable.

[0031] At the top layer, the active disconnect box 12 encapsulates several key components: a protected 12V power supply 14, an activation system 16, an activator unit 18, and a pyrotechnic fuse 20. The activator unit 18 contains both a current measuring device 22 and an internal detonator driver 24. The pyrotechnic fuse 20 is located downstream of the activator unit and is the final load in the trigger circuit.

[0032] The system is powered by a 12V battery 26. This battery is connected in series with a relay 28, which allows for manual or controlled disconnection of the main power supply. The output of relay 28 is fed into the vehicle's 12V IN line into the active disconnect box 12.

[0033] Inside the active disconnect box 12, the vehicle's 12V IN is connected to a protected 12V power supply 14. This module includes an isolation diode 30 that blocks reverse current, and an internal power supply 32, such as a backup capacitor or auxiliary battery. The protected output from this unit supplies voltage to both the activation system 16 and the activator unit 18 (including the burst tube driver 24).

[0034] In this example, the activation system 16 comprises two parallel branches, each containing 10 MΩ pull-up resistors 34 and 36 and N-channel MOSFETs 38 and 40. These branches are powered by a protected 12V line. The gate and source of each MOSFET are connected via a cutoff circuit 42. When the cutoff circuit 42 is intact, the gate remains low relative to the source, thus keeping MOSFETs 38 and 40 off. If the cutoff circuit 42 is open, the gate voltage rises via the pull-up resistors 34 and 36, thereby turning on MOSFETs 38 and 40. Current can then flow from the drain to the source, forming a path from 12V through the detonator 24 and activating the pyrotechnic fuse 20.

[0035] In this example, the cut-off loop 42 is routed through three separate entry points in vehicle 10: driver's compartment 44, left window 46, and right window 48. These branches are electrically connected such that cutting off any one branch disconnects the ground reference of the MOSFET gate, allowing the gate to be pulled high and the circuit to close. The trigger line HI in the figure represents the high-side 12V path connected to pull-up resistors 34 and 36. The trigger line LO is a shared ground connection routed through the cut-off loop path.

[0036] As described above, the activator unit 18 includes a current measuring device 22 and a bursting tube driver 24. The current measuring device 22 monitors the current flow through the high-voltage bus and reports this information to the VCU 50 via the CAN bus 52. The bursting tube driver 24 can receive activation commands and apply drive signals to the pyrotechnic fuse 20. The VCU 50 is responsible for issuing those commands via communication using the CAN bus 53. It is individually powered and grounded and connected to the chassis ground.

[0037] The burst tube driver 24 sends its output to the pyrotechnic fuse 20, which includes a burst tube 54 and a 2.2 Ω resistor representing the characteristic load of the burst tube 54. This resistor is connected between two terminals associated with the burst tube driver 24. The burst tube 54 is activated when a voltage is applied across these two pins either through the burst tube driver 24 or through an alternative MOSFET path in the activation system 16.

[0038] The detonator 54 is driven by two lines: trigger line HI and trigger line LO. Trigger line HI is pulled to 12V when activated, while trigger line LO is pulled to ground. These lines originate from activation system 16 and run directly across detonator 54. Activation system GND provides the current return path.

[0039] The manual maintenance disconnector 56 is installed in series with the vehicle's 12V IN. This switch provides a physical disconnection method for maintenance or repair, thereby disconnecting the 12V supply to the active disconnector 12 when disconnected.

[0040] The system provides two separate methods to activate the pyrotechnic fuse 20. The first is via software control, which uses the detonator driver 24 commanded by the VCU 50 via CAN. The second is a hardware path, which uses the MOSFETs 38 and 40 in the activation system 16 and the cut-off circuit 42 as triggering mechanisms. In both cases, when a voltage is applied across the detonator 54, the pyrotechnic fuse 20 is triggered and the high-voltage bus is mechanically interrupted.

[0041] The activation system described above uses a discrete N-channel MOSFET with a gate-source circuit that includes a physical cutoff circuit and a pull-up resistor to control the activation of the detonating tube in a pyrotechnic fuse. An alternative implementation can replace the discrete MOSFET and resistor with an integrated gate driver integrated circuit (IC). This IC can incorporate built-in pull-up functionality, undervoltage lockout, and gate discharge circuitry. The gate input can still be controlled via an external cutoff circuit connected via an enable pin or logic input, but integration reduces discrete wiring.

[0042] Another possible configuration utilizes a dual-redundant solid-state switch architecture. In this version, two independently controlled power MOSFETs or GaN FETs can be connected in series between the protected 12V power supply and the burst terminal. Each switch will be managed by a separate disconnect circuit routed through different physical areas of the vehicle. The switch will only close when both circuits are open, thus providing a higher level of fault containment through logical AND activation. A microcontroller can be used as a monitoring element to monitor the continuity of the disconnect circuit via high-impedance sensing and provide diagnostic data via CAN, without directly participating in the activation path.

[0043] Another variation may involve using a relay or pyrotechnic actuator with an integrated mechanical release mechanism triggered by a small, high-energy capacitor bank. In this method, cutting off the circuit activates a passive circuit that releases stored energy into the actuator when the circuit is broken. This method eliminates the need for a continuous low-leakage current path and uses an energy storage device to deliver the necessary pulse to ignite the detonating tube. The triggering circuit can be designed entirely using passive components such as resistors, diodes, and Zener-controlled charging paths.

[0044] The algorithms, methods, or processes disclosed herein may be delivered to or implemented by a computer, controller, or processing device, which may include any dedicated electronic control unit or programmable electronic control unit. Similarly, the algorithms, methods, or processes may be stored in many forms as data and instructions executable by a computer or controller, including but not limited to information permanently stored on non-writable storage media such as read-only memory devices and information reproducibly stored on writable storage media such as optical discs, random access memory devices, or other magnetic and optical media. The algorithms, methods, or processes may also be implemented as software executable objects. Alternatively, the algorithms, methods, or processes may be wholly or partially embodied using suitable hardware components (such as application-specific integrated circuits, field-programmable gate arrays, state machines, or other hardware components or devices, or firmware, a combination of hardware and software components).

[0045] The terms used in this specification are descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of this disclosure.

[0046] As previously described, features of the various embodiments can be combined to form other embodiments that may not be explicitly described or shown. While the various embodiments may have been described as providing advantages over other embodiments or prior art implementations in one or more desired characteristics, or being preferred over other embodiments or prior art implementations, those skilled in the art will recognize that one or more features or characteristics can be compromised to achieve desired overall system properties that depend on the specific application and implementation. Therefore, embodiments described as less desirable than other embodiments or prior art implementations in terms of one or more characteristics are within the scope of this disclosure and may be desirable for a particular application.

[0047] According to the present invention, a vehicle electrical system is provided, comprising: a high-voltage bus; a pyrotechnic fuse configured to mechanically interrupt the high-voltage bus when activated; a pair of switches and a disconnection circuit, the pair of switches and the disconnection circuit being configured such that, in response to an interruption in the disconnection circuit, the switches supply power to the pyrotechnic fuse to activate the pyrotechnic fuse.

[0048] According to one embodiment, the switch is a field-effect transistor.

[0049] According to one embodiment, the invention is further characterized by a pair of resistors, each of which is directly connected to the gate of one of the field-effect transistors.

[0050] According to one embodiment, the invention is further characterized by a power supply and a disconnect switch, wherein the resistor can be connected to the power supply via the disconnect switch.

[0051] According to one embodiment, the pyrotechnic fuse includes a bursting tube, the source of one of the field-effect transistors is directly connected to a pin of the bursting tube, and the drain of the other field-effect transistor is directly connected to another pin of the bursting tube.

[0052] According to one embodiment, the invention is further characterized by a power supply and a disconnect switch, wherein the drain of one of the field-effect transistors can be connected to the power supply via the disconnect switch, and the source of the other field-effect transistor is directly connected to the chassis ground.

[0053] According to one embodiment, the invention is further characterized by a burst tube driver configured to provide power to the pyrotechnic fuse to activate it.

[0054] According to one embodiment, the invention is further characterized by a power supply and a disconnect switch, wherein the burst tube driver can be connected to the power supply via the disconnect switch.

[0055] According to one embodiment, the invention is further characterized by: a current sensor configured to detect current on the high-voltage bus; and a controller programmed to command the burst tube driver to supply power to the pyrotechnic fuse in response to the magnitude of the current exceeding a certain value.

[0056] According to one embodiment, the switch is an N-channel metal-oxide-semiconductor field-effect transistor.

[0057] According to one embodiment, the invention is further characterized by a housing, wherein the pyrotechnic fuse and the switch are disposed within the housing.

[0058] According to the present invention, a method includes: switching a pair of field-effect transistors from non-operation to operation due to an interruption in the vehicle's cut-off circuit, such that the field-effect transistors provide power to the burst tube of a pyrotechnic fuse to activate the pyrotechnic fuse and mechanically interrupt the high-voltage bus associated with the pyrotechnic fuse.

[0059] In one aspect of the invention, the method includes commanding a burst tube driver to provide power to the burst tube to activate the pyrotechnic fuse.

[0060] In one aspect of the invention, the command is in response to the magnitude of the current on the high-voltage bus exceeding a certain value.

[0061] According to the present invention, a vehicle is provided having: a high-voltage bus; a disconnect circuit; and a disconnect box, the disconnect box including: a pyrotechnic fuse configured to mechanically interrupt the high-voltage bus when activated; an activation system configured to supply power to the pyrotechnic fuse in response to a disconnection in the disconnect circuit to activate the pyrotechnic fuse; and a bursting tube actuator configured to supply power to the pyrotechnic fuse in response to a command to activate the pyrotechnic fuse.

[0062] According to one embodiment, the disconnect box further includes a power supply configured to selectively provide power to the activation system and the burst tube driver.

[0063] According to one embodiment, the activation system includes a pair of switches configured to activate in response to the disconnection in the cut-off circuit.

[0064] According to one embodiment, the switch is a metal-oxide-semiconductor field-effect transistor.

[0065] According to one embodiment, the invention is further characterized by a 12V battery configured to selectively connect to the disconnect box.

[0066] According to one embodiment, the invention is further characterized by a controller programmed to generate the command in response to the magnitude of the current on the high-voltage bus exceeding a certain value.

Claims

1. A vehicle electrical system, comprising: High-voltage bus; A pyrotechnic fuse configured to mechanically interrupt the high-voltage bus when activated; as well as A pair of switches and a cut-off circuit are configured such that, in response to an open circuit in the cut-off circuit, the switches supply power to the pyrotechnic fuse to activate the pyrotechnic fuse.

2. The vehicle electrical system of claim 1, wherein the switch is a field-effect transistor.

3. The vehicle electrical system of claim 2, further comprising a pair of resistors, each of the pair of resistors being directly connected to the gate of one of the field-effect transistors.

4. The vehicle electrical system of claim 3, further comprising a power supply and a disconnect switch, wherein the resistor is connectable to the power supply via the disconnect switch.

5. The vehicle electrical system of claim 2, wherein the pyrotechnic fuse comprises a bursting tube, the source of one of the field-effect transistors is directly connected to a pin of the bursting tube, and the drain of the other field-effect transistor is directly connected to another pin of the bursting tube.

6. The vehicle electrical system of claim 5, further comprising a power supply and a disconnect switch, wherein the drain of one of the field-effect transistors is connectable to the power supply via the disconnect switch, and the source of the other field-effect transistor is directly connected to chassis ground.

7. The vehicle electrical system of claim 1, further comprising a burst tube actuator configured to provide power to the pyrotechnic fuse to activate the pyrotechnic fuse.

8. The vehicle electrical system of claim 7, further comprising a power supply and a disconnect switch, wherein the burst tube driver is connectable to the power supply via the disconnect switch.

9. The vehicle electrical system of claim 7, further comprising: A current sensor configured to detect the current on the high-voltage bus; And a controller programmed to command the burst tube driver to supply power to the pyrotechnic fuse in response to the magnitude of the current exceeding a certain value.

10. The vehicle electrical system of claim 1, wherein the switch is an N-channel metal-oxide-semiconductor field-effect transistor.

11. The vehicle electrical system of claim 1, further comprising a housing, wherein the pyrotechnic fuse and the switch are disposed within the housing.

12. A method comprising: Due to the interruption in the vehicle's cut-off circuit, a pair of field-effect transistors are switched from being inactive to being active, causing the field-effect transistors to supply power to the burst tube of the pyrotechnic fuse to activate the pyrotechnic fuse and mechanically interrupt the high-voltage bus associated with the pyrotechnic fuse.

13. A vehicle comprising: High-voltage bus; Disconnect the circuit; as well as A disconnect box, the disconnect box comprising: a pyrotechnic fuse configured to mechanically interrupt the high-voltage bus when activated; an activation system configured to supply power to the pyrotechnic fuse in response to a disconnection in the disconnection circuit to activate the pyrotechnic fuse; and a burst tube actuator configured to supply power to the pyrotechnic fuse in response to a command to activate the pyrotechnic fuse.

14. The vehicle of claim 13, wherein the disconnect box further includes a power source configured to selectively supply power to the activation system and the burst tube driver.

15. The vehicle of claim 13, wherein the activation system comprises a pair of switches configured to activate in response to the disconnection in the cut-off circuit.

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